1. Field of the Invention
The present invention relates to a system for flushing out contaminants that clog the fluid pathway of an autotransfusion system, and more specifically to a filtration system for a chest drainage unit (CDU) that includes a valve means for generating a reflux action that clears large blood clots that form in the fluid pathway. More particularly, this invention relates to a flow-sensitive valve cap and related method of use for flushing large blood clots back into the CDU's collection chamber while preventing re-entry of the same into the fluid pathway.
2. Prior Art
A CDU is an apparatus for suctioning gases and liquids from the pleural cavity of patients. The pleural cavity lies within the rib cage above the diaphragm and is surrounded by the pleural membrane. The pleural cavity contains both lungs, which in their normal expanded state fill the pleural cavity. Several conditions and diseases such as interventional surgery, trauma, emphysema and various infections can cause a build up of liquid and gases around the lungs in the intrapleural space. When this happens, it causes the lungs to collapse to a volume much less than that of the pleural cavity, thereby severely impairing breathing functions of the patient. The lungs can be re-expanded to their normal state to fill the pleural cavity by draining the liquid and gases from the intrapleural space using a chest drainage unit.
CDUs are also used during autotransfusion for recovering autologous blood from the patient's pleural and mediastinal cavities and transfusing that blood back into the patient. Autotransfusion offers significant advantages over normal transfusion procedures which use homologous blood from other humans. Autologous blood reduces the risk of adverse reactions and transmission of infectious disease while supplying a readily available and safe source of compatible blood to the patient. For these reasons, CDUs are being designed to both evacuate fluids from the intrapleural space and autotransfuse shed autologous blood back into the patient.
Various devices have been developed to drain and collect fluids such as blood from the intrapleural space for subsequent autotransfusion. U.S. Pat. No. 4,114,416 to Karwoski et al. illustrates the prior art development of autotransfusion chest drainage units. The device includes a collection chamber for the collection of fluid from the pleural cavity, a water seal chamber for preventing passage of gas from the atmosphere into the patient's pleural and mediastinal cavities, and a manometer chamber for regulating the degree of vacuum in the system. An inlet port of the collection chamber is connected to the patient's pleural cavity via a thoracotomy tube that deposits shed blood and gases into the collection chamber. As the shed blood enters the inlet portion of the collection chamber, a large area gross filter, such as a fabric or an open-pore foam filter, is used to remove blood clots and gross particles from incoming fluids. Once filtered, the blood collects at the bottom portion of the collection chamber until reinfusion is effected and the blood is drained through an outlet port located at the bottom portion of the collection chamber. The Karwoski et al. device is also placed in fluid flow communication with a blood compatible pump set through tubing that connects the pump to the outlet port and permits the collected blood to drain therethrough for reinfusion to the patient.
One drawback with the Karwoski et al. device is that no provision is made for clearing out blood clots that develop after the blood has been filtered and pumped from the collection chamber. In some instances, large blood clots may form even after the blood has been filtered prior to reinfusion back to the patient. If these clots are not removed or cleared out when the blood is reinfused back to the patient from the CDU, the fluid pathway between the patient and the filtration site inside the CDU will become clogged and unusable as the blood exits the Karwoski et al. device. Further, a microaggregate filter that is normally interposed between the outlet of the collection chamber and the patient can also become clogged with blood clots and unusable. As a result, a practitioner will have to take the time to replace the entire CDU as well as the blood infusion set and attendant tubing which exposes the patient to undesirable risks caused by the time delay in clearing or replacing the fluid pathway between the CDU and the patient while reestablishing the autotransfusion process. Moreover, interruption of the autotransfusion process might require the practitioner to substitute homologous blood that could be contaminated or incompatible with the patient's own blood.
As of yet, nothing in the prior art has addressed the problem of unclogging the fluid pathway between the filtration site and the patient of blood clots that form after filtration. Specifically, there has been no design consideration that permits the practitioner to use the CDU as a means for clearing out clogged tubing of blood clots without a major interruption of the autotransfusion process. Further, there has been no procedural consideration setting forth a method for clearing out the fluid pathway of blood clots after the blood has passed through the filtration site during reinfusion to the patient.
There therefore exists a need in the art for a filtration system that includes a valve cap in combination with a spike port assembly that permits the practitioner to employ a method of clearing out blood clots that develop after filtration without major interruption of the autotransfusion process.